The present invention relates to a pharmaceutical composition containing ezrin mutated on tyrosine 353, for controlling cell survival and apoptosis and for use preferably in the prevention and/or treatment of tumors.
Throughout this application, various publications, issued patents and published patent specifications are cited. The bibliographic citation for each reference may be found at the end of the specification, immediately preceding the claims or within this specification. The disclosures of these publications are hereby incorporated by reference into the present disclosure to more fully describe the state of the art to which this invention pertains.
Ezrin was characterized as a component of brush-border and placental microvilli in the early 1980s (Bretscher et al., 1983). The family now consists of four members in vertebrates, namely ezrin, radixin, moesin (ERM proteins) and merlin (moesin-ezrin-radixin-like protein: also named schwannomin).
The structure of all family members consists of an amino-terminal globular domain followed by an a-helical region and a carboxy-terminal domain. The family belongs to the band 4.1 superfamily on the basis of sequence homology of the amino-terminal domain with the erythrocyte membrane-cytoskeleton linker protein band 4.1.
Ezrin, radixin and moesin are thought to work as cross-linkers between plasma membranes and actin-based cytoskeletons (Arpin et al., 1994).
Phosphorylation may regulate the conformation of the proteins induced by several growth factors. ERM proteins could be regulated by phosphorylation of different protein domains, including Tyr145 located in the amino-terminal domain and Tyr353 in the xcex1-helical domain. These two residues are phosphorylated by EGF receptor (Krieg et al., 1992). Phosphorylation of the carboxy-terminal domain may also regulate the actin-binding ability of ERM proteins (Vaheri et al., 1997, Tsukita et al., 1997).
The authors of the present invention have recently shown that ezrin is an effector of hepatocyte growth factor-mediated migration and morphogenesis in epithelial cells (Crepaldi et al., 1997).
The authors of the present invention have now discovered that ezrin mutated on tyrosine 353 as shown in FIG. 1 impairs the ability of cells to survive in a collagen matrix, more particularly in a collagen type I matrix, and induces apoptosis, that is to say cell death. Such apoptosis could be due to a disruption of the signal transmission mediated by molecules of adhesion. In vivo, normal cells lie on a basal membrane which does not contain collagen type I. Tumor cells, and more particularly metastatic cells, may contact the extracellular matrix which contains collagen type I and are thus sensitive to the effect of ezrin mutated on tyrosine 353. Consequently ezrin mutated on tyrosine 353 is a good candidate for the prevention and/or treatment of tumors. Furthermore, ezrin mutated on tyrosine 353 could be useful to prevent metastasis and/or to lead to the apoptosis of migrating tumor cells involved in metastasis. which is a phenomenon due to a disruption of cell adhesion.
A subject of the present invention is thus a pharmaceutical composition containing an effective amount of ezrin mutated on tyrosine 353, or a functional fragment or derivative thereof, in association with a pharmaceutically acceptable carrier.
A further subject of the present invention is a pharmaceutical composition containing an effective amount of naked DNA or RNA encoding ezrin mutated on tyrosine 353, or encoding functional fragments or derivatives thereof, in association with a pharmaceutically acceptable carrier.
A still further subject of the present invention is a pharmaceutical composition containing an effective amount of a vector comprising an insert of DNA or RNA encoding ezrin mutated on tyrosine 353, or encoding fragments or derivatives thereof.
The pharmaceutical compositions of the invention are more particularly useful for the prevention and/or treatment of tumors, namely for the prevention and/or treatment of metastasis.